Electromagnet



Patented Jan. 11, 1944 UNITED STATES .PATENT OFFICE EmcraoMAGNE'r Eawa'ra J. Martin, New orleans, La. Appunti@ May 31, 1941, sensi No. 396,124

(ci. ris-341) l3Claims.

are spaced apart from the frame III to form guideways I1 for a purpose to be described later.

The coil I2 is conventional.' the same comprising an insulated conductor I8 wound onto a form, suitable insulation being provided between adjacent layers of turns and dipped into insulating material, which material serves to bind the turns together.' and also serves to bind the adjacent layers of turns to the insulation provided between them. The coil is then taped with insulating material, a rigid construction A still further object of vthe invention is to provide an electromagnet having improved means for guiding and steadying the operation of the moving armature within the coil.

' With the foregoing and other objects in view,

' the invention'will be more fully described hereinafter, and will be more particularly pointed v out in the claims appended hereto.

In the drawing, wherelike symbols refer to like 'or corresponding parts throughout the sev- (eral views Figure 1.

Figure 2- is*v an explodedfperspective view' of 'j the electromagnet shown in Figure 1, and, 1

Figure 3 is a modiiied form lof the invention. Referring 'more' particularly -to the drawingr and to Figures 1 and 2, one form of the invention is shown-as applied to an electromasnetl which` comprises essentially a magnetic frame e I0, a' movable amature II` and an operating coil, I2.` In order to permit the emcient operation 4'with alternating current, the frame Il andarmaturev II are built up of a multiplicity of thin v .laminations of magnetic material as indicated in the drawing. Each of the superimposed laminations constituting the frame I3 is of c-shape in order to provide an opening I3 through which the armature II operates within the coil I2. The closed end of the G-frame is provided with a projecting portion I4 in alinexnentwithy the opening4 I3.

The laminations are clamped by opposing pairs of supporting members I5 and I3 and heldtogether by rivets or the like. The two opposing supports I5 at the end of the frame I0 having is a perspective view of an electromagnetl embodying the present invention,

being obtained with anopening I9 through the center.

'I'he coil is placed between ends of the frame ,IIi'so that the opening I9 in the coil is ln alinement with the projectiony I4 and with the opening I3 provided between the inwardly extending ends 20 and 2i of the magnetic frame.

The operation of the armature II back and forth through the coiland frame sometimes injures both the frame and coil while emitting a .chattering or humming noise. In order to rigidly secure the coil in position and eliminate the noises referred to, the present invention contemplates provision of a guide for the movement of the armature through the coil.

Generally such guide meansoomprises a single sheet of brass kmaterial bent to form a square tube and fitting in`4 the coil opening and secured to the magnetic frame.

As illustrated in Figure 2, the guide as indiy. cated by the numeral 22 is substantially square in cross-section although 'any suitable shape may be given in same. vSuch guide 22 is preferably formedy from a single sheet of brass material-bent to provide a one piece square tube with inwardly extending legs23 and 24 spaced from each otherf Tl'iis spacing will permit a slight contraction before insertion and a corresponding expansion after insertion' of the guide 22 in coil I2 to provide a snug assembly of coil and guide.

As thus constructed, the guide 22 provides ample bearing surfaces for movement of the armature II in its movement through the guide. iAt the same time, the guide 22 snugly encompasses the armature II to prevent the chatterthe opening I3 therein bridge the sides of this 'I'hese supports also serve as guides to conne the armature II in proper operating relation in the opening I3. The other pair of supportingmembers I8 at the opposite or rear end of the frame ing or humming noise referred to and which is objectionable. I

It will be noted that the guide 22 provides a continuous bearing surface for the armature except for the slight clearance between legs 23 and 24. The opposed sides 25 o! the guide 42 have reduced portions 26 and 21 at the rear thereof or in the portions which engage in th'e guideways I1. The reduced portions 21 form tabs to be utilized in the assembly of the guide to the frame I0.

In assembling the device, the coil I2 iscplaced Within the frame ID whereby the opening I9 of the coil is in registry with the projection I4 and opening I3 of the frame; Then the guide 22 is inserted through the opening I3 and opening I9, the reduced portions 26 and 21 sliding in the guideways I1 with the reduced portions 21 projecting therefrom. The tabs 21 are subsequently turned back over the guideways I1.

Thus by means of this construction it will be observed that the guide 22 not only secures the coil I2 firmly in place and in alinement with' the frame I but it also protects the coil from injury by the armature II and at the same time affords suitable bearing surfaces for the armature to prevent the objectionable noise referred to. Furthermore, the coil is readily assembled within the frame and replacements can be made with a. minimum of effort.

Referring now to th'e modified form of the invention illustrated in Figure 3, this form is'to be used with the same frame and armature illustrated in Figures 1 and 2. In this form of the invention, however, the coil 28 is wound or formed directly on the guide 22 instead of being inserted separately therein as in Figures 1 and 2. Thus the coil 28 and guide 22 are handled as a single unit to facilitate assembly and replacement to and from the frame I0.

This form of the invention has tabs 21 which are similar to those illustrated in Figures 1 and 2 and are adapted to enter the guideways l1 and be turned back as in those gures. However the forward portion of the sleeve 22 is provided with slits 29 which form additional tab members 3U, 3|, 32, 33 and 34. As such, when the coil and sleeve are assembled in the frame, the tabs 30, 3 I, 32, I33 and 34 are bentV back against the frame I0 to furnish additional support and to keep the coil in position.

In either form of the invention, the guide member 22 serves not only to rigidly secure the coil in position and protect it from damage by movement of the armature Il but by providing a guide for the armature prevents undesired vibration or oscillation of the armature. The square tube type of guide means not only simplifies construction of the guide but also provides a great deal of bearing surface for the armature. 'I'he tabs on the guide member permit an easy assembly and replacement in the frame I0.

It is -obvious that various changes and mod- .'lcations may be made in the details of construction and design of the above specifically described embodiment of this invention without departing from the spirit thereof, such changes and modifications being restricted only by the scope of the following claims:

agis claimed is:

an electromagnet comprising a magnetic frame, an operating coil provided with a bore extending axially therethrough, a guide member having greater length than said bore, said guide being of tubular form and constructed of an integral piece of material the side edges of which are disposed in spaced parallel relation to define a longitudinal slot extending from end to end of the guide member and permitting contraction and expansion of the guide member, said guide member being of a cross-sectional size requiring a slight contraction to enable it to be passed through the bore of the coil whereby when placed in position Within the bore of the coil and released it will expand and grip the walls of the coil bore, an armature adapted for slidable movement in said guide, and means to removably connect said guide member to the magnetic frame,

2. In an electromagnet comprising a magnetic frame, an operating coil provided with a bore extending axially therethrough, a guide member having greater length than said bore, said guide being of tubular form and constructed of an integral piece of material the side edges of which are disposed in spaced parallel relation to define a longitudinal slot extending from end to end of the guide member and permitting contraction and expansion of the guide member, said guide member being of a cross-sectional size requiring a slight contraction to enable it to be passed through the bore of the coil whereby when placed in position within the bore of the coil' and released it will expand and grip the Walls of the coil bore, an armature adapted for slidable movement in said guide, means to removably connect said guide member to the magnetic frame, said magnetic frame having supports secured thereto and shaped to provide guideways between the frame and the supports in line with the side walls of the guide member, and said removable connecting means comprising extensions carried by opposite sides of said guide member at one end thereof, said extensions being inserted into said guideways adjacent to the magnetic frame, and tabs carried by the ends of the extensions and bent over said supports to secure the guide member and coil to the frame.

3. A tubular guide member for an electromagnet comprising an integral piece of material slotted longitudinally to permit contraction and expansion thereof, one end of said guide member having a pair of tabs extending therebeyond and adapted to be bent over.to secure said guide member to one end of a frame, the other end of said guide member being' slotted to provide tabs in excess of the firstmentioned pair of tabs for securing the guidato the other end of a frame, and an operating coil wound upon and permanently secured to said guide member between the end portions.

EDWARD J. MARTIN. 

